At this point in the 21st century, in the midst of the Age of Plastic, we all assume that this is an indispensable material, without which it would be impossible to imagine our current modus vivendi , for many reasons. The usefulness and necessity of plastic is as undeniable as the fact that its use and exploitation comes hand in hand with a growing controversy, considering that the plastic waste resulting from the last decades has been accumulating uncontrollably.
Therefore, environmental authorities are constantly warning about the consequences of this problem and the need to face it. As introduction to the topic we will address, it should be said, however, that we are used to calling ‘plastic’ a variety of very different materials and components, both in terms of their nature and in their usefulness.
The fact is that the typology of plastics is extensive, and the environmental impact they produce as well as the need to use them, differs greatly depending on the type we are talking about.
In this post we focus on a thermoplastic, polypropylene (PP), one of the most used and exploited plastics in the industry We will highlight its role in products that have a long shelf life, we will expose some details about its recyclability and recycling and we will see the possibilities of application of products manufactured in post-consumer PP, present and future.
We currently have a lot of information on polypropylene and its characteristics, but it is necessary to briefly address the differential points with respect to other plastics, in order to understand its potential and why its exploitation developed on a massive scale.
The polymer we are dealing with in this post did not emerge until the second half of the 20th century, at the height of the development and sophistication of plastic products, thanks to G. Natta and K. Ziegler, and the boom in its commercialization takes place in the 80s. It is, therefore, a plastic of recent use. Why has it become so popular, taking ground away from other plastics? What makes it truly unique?
Polypropylene is a thermoplastic polymer whose differential point lies in its versatility to transform into an almost infinite variety of products, and therefore, in its high number of applications. It is a semi-rigid plastic that combines hardness, strength and lightness; which has an optimal elastic recovery capacity, a great thermal resistance (higher than that of polyethylenes) and which also has a very competitive cost.
Polypropylene as a reusable plastic
A fundamental factor to be considered on the plastic and his relation with the sustainability is the use that is given to the plastic product: if it has a long service life or if, by contrast, it is a disposable product.
The main problem of plastics lies in the huge amount of waste that is generated, mainly from single-use plastics (bottles, cover, straws, films,etc.), and the difficulty of management of those. These products are, mainly, packaging. Packaging represents, according to official sources, 39% of the total of plastic products used in Europe, of which 40% are single-use packaging.
Although the PP has a remarkable presence in the packaging sector, his presence in single-use products is less remarkable than that of other plastic materials, such as PET (polyethylene terephthalate). Many food-grade polypropylene containers such as glasses or lunch boxes, or others like chemical storage bottles, are also reusable and conserve his initial properties. This is an important difference. The PP has a big importance in those plastic products that have an longer service life, this means, that can be used extendedly while conserving its performance. The sectors to which PP is most targeted are packaging (45%), followed by automotive (28%) and construction (10%) (Source: www.plasticseurope.org).
Here we have some uses of products manufactured in polypropylene:
- Urban, commercial and office furniture (benches, tables, chairs, etc.).
- Medical applications. Prosthesis, sterilisation containers for surgical instruments, etc.
- Construction and sanitation sector: Floors and paving, tiles, construction tools such as debris chutes and mortar skips, catch basins, channel drains, etc.
- Components and pieces for the automotive sector.
- Logistics: Pallets and other reusable packaging.
- Reusable containers. Food use, like lunch boxes and glasses, or chemical storage containers such as petrol cans, etc.
- Textile. Products from the fashion and sports industry (sportswear equipment, underwear, etc.).
Sustainability and recyclability
It is worth mentioning here that, as part of the demonisation of plastic, there is a tendency to think that a product made of any other material (cardboard, glass, wood or steel) is in itself a greener product than a product made of plastic, but the truth is that the use and exploitation of all these materials has an ecological impact of equal or greater proportions; for example, we could mention the impact of the steel industry on water and greenhouse gases, or the forestry impact of the cardboard and paper industry. Moreover, the thoughtless substitution or combination of plastics with these materials often leads to the use of more energy in processing, and makes it more difficult – or impossible – to recycle products.
Greenwashing plays a key role here. This is why the sustainability of a product does not depend on the material itself, but on how the product is consumed and manufactured, together with the management of the waste that is generated.
PP is a strong and durable material, suitable for circular use. This reuse will provide a more sustainable and environmentally friendly alternative compared to other materials that are less suitable for circularity.
Regarding the energy used in the production of plastics, the promotion of recycling and reuse of these materials will allow to reduce significantly the use of that energy, since it will be possible to obtain the plastics from other plastics, depending less on oil.
The PP, a fully recyclable material
At this point, it is necessary to distinguish between two basic forms of recycling:
As for the recyclability of PP, in contrast to plastics such as PVC (polyvinyl chloride) or PS (polystyrene), whose composition and additives make it difficult to recycle, it has a high degree of recyclability and can be repeatedly subjected to melting and remodeling processes at a relatively low cost. In addition, although the quality of the product obtained from post-consumer recycling can never be exactly the same, the PP largely maintains its characteristics, so it is perfectly valid to have more than one useful life.
However, although it is a material with great potential for post-consumer recycling, the PP recycling rate is still very low, mainly due to the difficulty and cost of managing the separation for the subsequent recycling of waste. As there is a lower volume of post-consumer recycled PP on the market, the price is higher, which makes it difficult for processing companies to acquire it.
However, the potential of this material is gradually materializing, and more companies and institutions dedicated to the recycling of post-consumer plastic products are emerging. This recycling has increased by 80% in the last decade, and it is expected to continue growing in the coming years. As its volume increases in the market and the price becomes more competitive, its use will be encouraged by transforming companies, which in turn will be able to optimize the cost of their processes and improve their brand image, thus contributing to closing the circle.
There are currently many companies that manufacture products with post-consumer recycled PP materials, and experts agree that the growth in the next decade will be remarkable. The road to circularity is unavoidable and unstoppable, and to the post-consumer PP applications that we will quote below, new ones may be added in the short-medium term:
- Automotive: about 40% of the plastic in a vehicle is polypropylene.
Companies such as Volvo, Ford or Renault already create their models with parts from post-consumer PP, such as bumpers, engine covers, tool boxes, dashboards, doors, etc., and estimate a significant growth in the use of this material in the coming years.
- Food packaging: advertising labels are also included. In order to be applied to food packaging, the PP must undergo a chemical recycling process.
- Packaging for cosmetics and other chemical products: detergents, softeners, fuels, etc… PP is resistant to chemically aggressive acids and solvents, making it suitable as a durable material for the storage of these products.
- Logistics: returnable packaging, for areas such as E-commerce. Pallets and pallet boxes. Most logistics and distribution companies currently use millions of disposable packages per year and are progressively incorporating returnable packaging solutions.
- Street and shop fittings. Illuminated signs, sandboxes, planters, fences, rubbish bins, shelves, supermarket trolleys and baskets, etc. Recycled PP is immune to rodents, pests, fungi, bacteria and moisture. It has a high thermal resistance (it adapts well to the climate) and is also non-combustible. It is a thermally and electrically insulator.
- Private furniture. Tables and chairs, cupboards, garden furniture, etc. The use of post-consumer recycled PP for the manufacture of plastic wood can be a suitable alternative to natural wood.
- Construction: flooring and paving such as decking, tiles, bricks, roofing shingles, fibres, planks or pipes. As mentioned above, recycled polypropylene is an ideal material for these purposes, as it is able to withstand many years of weathering in good conditions.
The processing of post-consumer plastics for road construction is currently being studied by institutions such as the National University of Colombia (UNAL).
- Textile: PP is a common component in the textile industry. It is more resistant to fire than wool and is also resistant to environmental factors such as sun, mould, water and bacterial influences, which makes it an interesting option for its recycling for further use in clothing fibres.
- Household appliances and utensils: plastic components in hoovers, refrigerators and washing machines.Utensils such as brooms and dustpans. Also suitable for items such as suitcases (as opposed to ABS plastic, whose rigidity can facilitate breakage).
- Stationery: covers for books and notebooks.
In times of Greenwashing, it is common to find advertising from some companies, which is related to sustainability, commitment to the environment or ecological products (especially when we talk about plastic). However, how do we really know what measures companies take to call themselves sustainable?
Regarding the products, it is essential to focus on international certifications. Placing an international certification label or seal on a product involves a strict process of compliance with requirements and processes; for example, these requirements allow us to verify that a product has a total or very high percentage of post-consumer recycled material, or that it has been produced by carrying out a sustainable industrialization process.
Therefore, it is very important to ensure that a certain product from recycled material is duly supported by existing certifications. Some of the most important ones are Blue Engel, OK Recycled or those issued by AENOR for recycled material.